Rust, caused by Puccinia helianthi, and blackleg, caused by Leptosphaeria maculans, are economically important diseases on sunflower and oilseed rape, respectively. In order to recommend the most effective disease management practices to growers, management strategies need to be evaluated as new tools are developed and pathogen populations change. The objectives of these studies were to; 1) evaluate the efficacy of foliar fungicides on rust in confection and oilseed sunflowers in the U.S. Northern Great Plains, 2) determine virulence phenotypes of Puccinia helianthi in the sunflower seed production region of Northern California, and 3) evaluate the seed applied fungicide adepidyn for efficacy of blackleg on oilseed rape in Northern Germany. Efficacy of 11 foliar fungicides against sunflower rust were demonstrated on both confection and oilseed sunflowers, however, yield differences were only observed in confection experiments. In total, 21 races of Puccinia helianthi were identified in the sunflower seed production region of California, of which 18 were reported for the first time. To the best of our knowledge, this work presents the only data generated from wild Helianthus annuus populations in the region, and results demonstrate the threat that rust on wild species presents to the commercial seed production industry. Results of experiments conducted to evaluate the suitability of the novel seed treatment adepidyn for management of blackleg demonstrated efficacy under climate-controlled conditions, but efficacy was not observed in field studies. Results of these studies detail relevant and timely information that will help agriculture professionals better manage these economically important diseases of oilseed crops.